A problem with a comparison block

[Shohadawy]

I'm using a comparison block "LE". The block does not generate an output although the condition of the comparison is correct and all the contacts before the "EN" of the block is true. I tried connecting the "EN" directly to the power rail in the ladder but the same problem exists. What may be the cause of such problems?

 

[Maitomies]

Can you post the code here? I assume you are using S7.

 

[Lancie1]

What may be the cause of such problems?

A "double-coil" - reusing the same output BELOW the comparison block, where another rung turns off the output. Remember that the PLC will do what it was LAST told to do.

 

[bluenoser337]

Is the program block (or subroutine) that contains the comparison being scanned (or called from the main program)?